Sudden spikes in global temperatures that occurred 50-55 million years ago were caused by thawing of permafrost in Antarctica and northern high latitudes, according to recent research.

The trigger for this sudden destabilization was a variation in orbital configurations that resulted in warmer polar summers.

This model also provides an analogue for the releases of carbon from modern permafrost caused by current man-made global warming.

Modern permafrost volumes are smaller than the estimates for those of 55 million years ago, but will nevertheless amplify the climatic effect of fossil fuel consumption and will provide continuing warming feedbacks for centuries after human emissions cease.